It is known to use gas-liquid heat exchangers to cool compressed charge air in turbocharged internal combustion engines or in fuel cell engines, or to cool hot engine exhaust gases. For example, compressed charge air is typically produced by compressing ambient air. During compression, the air can be heated to a temperature of about 200° C. or higher, and must be cooled before it reaches the engine.
Various constructions of gas-cooling heat exchangers are known. For example, gas-cooling heat exchangers commonly have an aluminum core comprised of a stack of tubes or plate pairs, with each tube or plate pair defining an internal coolant passage. The tubes or plate pairs are spaced apart to define gas flow passages which are typically provided with turbulence-enhancing inserts to improve heat transfer from the hot gas to the liquid coolant.
In some gas-liquid charge air coolers, the aluminum core is enclosed within a housing, which is typically formed from a dissimilar material such as plastic. The housing typically includes coolant inlet and outlet openings which are sealingly connected to the coolant passages within the tubes or plate pairs. The housing also includes gas inlet and outlet openings and provides manifold spaces for the gas flow, and the gas flow passages of the core are open to the interior of the housing.
Typically there are gaps between the heat exchanger core and the housing. Along the sides of the core, the presence of these gaps is due partly to spacing between the tubes or plate pairs and the interior of the housing, and partly due to spacing between the edges of the turbulence-enhancing inserts and the interior of the housing. If left open, the gaps along the sides of the core will permit excessive bypass flow of the hot charge air, reducing the efficiency of the heat exchanger. Therefore, it is common for the housing to include bypass blocking elements having a comb-like profile with fingers extending into the spaces between the tubes or plate pairs. A heat exchanger with bypass blocking elements of this type is described in commonly assigned U.S. Provisional Patent Application No. 61/985,588 filed on Apr. 29, 2014, which is incorporated herein by reference in its entirety.
Due to the irregular shape of the core, it is difficult to provide a bypass seal which effectively blocks bypass flow, which is simple to manufacture and which will remain in place during manufacture and use of the heat exchanger.
There remains a need for gas-cooling heat exchangers which provide high reliability while avoiding excessive material and/or manufacturing costs.